Method for molding fibrous material

ABSTRACT

A device for producing a three dimensional shaped consolidated product. The device includes a rotary drum, defined as a rotary conveyor with a peripheral surface extending in circumferential direction with at least one product shaping area in the form of a cavity on said peripheral surface, the peripheral surface is pervious to air at least in the product shaping area, at least one material feed device to feed a base material into the at least one cavity, a vacuum device designed to generate a negative pressure at least in the at least one cavity, whereby the generated suction is directed towards the interior of the rotary conveyor, and whereby downstream of the material feed device at least one consolidating device is located such that at least a part of the filled cavity is subjected to a consolidating treatment whereby the base material at least partly will adhere to neighboring material.

This application is a divisional of U.S. patent application Ser. No.14/117,490, filed Apr. 3, 2014, which is the U.S. National PhaseApplication of International Application No. PCT/EP2012/058446, filedMay 8, 2012, which claims the benefit of priority to European PatentApplication No. 11166646.7, filed May 19, 2011, the entireties of whichare incorporated by reference herein.

TECHNICAL FIELD

The invention relates to a production device for producingthree-dimensional shaped fibrous mats for use as or in automotiveacoustic trim parts.

BACKGROUND ART

In the automotive industry fiber felt materials are used in a broadrange of products for sound insulation for instance in doors, rooflining, the floor area or as inner dash cladding. These products areformed and cut from large felt blanks to fit in the available space.Certain areas of such parts need higher amounts of material to obtainlocally higher noise attenuation. In particular, the inner dash situatedinside the passenger compartment and covering the wall between theengine bay area and the passenger compartment as well as certain areasof the floor covering have areas of increased fiber density. Feltproducts can be combined with other materials like mass layer to form aspring mass system or they can be used on their own to function as anacoustic absorbing layer. In all cases they can also be combined withaesthetic or acoustic covering layers, like thin nonwoven, needle punchor tufted carpets. These products need to follow the shape and contourof the area they need to cover as well as need to have fiber free areasfor instance for fastening means and to go around appliances in avehicle.

Fiber-felt products are classically produced from preformed constantdensity fiber mats containing binder fibers or resins, which are pressedin a heated mold and cut to obtain the desired form and stiffness. Adisadvantage of this method is that the grammage of the product dependson the density of the fiber mat and is therefore restricted, either thedensity of the mat used is too high for most of the surface area moldedor areas with a higher grammage can only be achieved by additionallysupplying the material by hand. This is time consuming and/or veryexpensive. Furthermore because the fiber mats are delivered as a rollgood or as pre-cut mats the production process is bound to render a lotof scrap material. Another disadvantage of the use of preformed fibermats is that they easily tear or break when they are pressed in moreextreme contoured molds. As the products can only be cut after a bindingstep, the scraps after cutting are of mixed heat set material thatcannot be used anymore in the process. The material is due to its mixednature difficult to recycle. This is a real problem for the automotiveindustry.

WO 2007/134812 describes an apparatus and a method for manufacturingnon-woven products. The apparatus comprises a rotating drum on which amaterial shaping area in the form of a mold cavity is provided. The moldcavity corresponds to the negative form of the wanted product. Withinthe drum, vacuum means are provided in order to suck air throughopenings in the wall of the mold cavity. Fiber material is fed to themold cavity by means of a fiber feed device. The fibers and hence thewanted product formed thereof are held in the mold by a negativepressure applied to the mold cavity, i.e. the material is held in themold by the suction airflow while the drum is rotating and is carryingthe mold cavity to a transfer device at which the formed material isde-molded. The vacuum compacts the fibers enough to keep a certainshape, however upon demolding the shape will flatten out as there is noreal binding between the fibers. This effect can worsen when syntheticfibers are used alone or in a blend as they are smoother and slideeasier.

After the de-molding step the formed unbonded material can be suppliedto a further mold, particularly a compression mold or can be directlysubjected to a heat treatment in a through hot air oven. In the furthermolding step a non-woven product with a final shape is formed from theformed material by applying heat and pressure.

The described method and apparatus has the advantage that at least theformed material can be manufactured in a continuous manner by means ofcontinuous rotation of the drum. However, as the formed material oftenconsists of unbonded fibrous material, the handling of the formedmaterial during and after the de-molding step until it is heat set isdelicate. During this process period the formed material can likely loseits wanted shape or even be disintegrated. In particularly fiber freeareas will fill up again during demolding. Furthermore the instablestructure of the formed material is difficult to put in a follow-up moldprecisely as a correction after lay down is not possible anymore. Slightoffsets can occur and the product finally produced is prone to rejectionat quality control, for not fitting the three-dimensional shape askedfor.

SUMMARY OF INVENTION

It is therefore an object of the invention to further develop theapparatus of the state of the art in particularly overcoming thedisadvantages.

The device described herein achieves this object. The device accordingto the appended claims comprises

-   -   a rotary drum, defined as a rotary conveyor with a peripheral        surface extending in circumferential direction with at least one        product shaping area in the form of a cavity on said peripheral        surface, the peripheral surface is pervious to air at least in        the product shaping area,    -   at least one material feed device to feed a base material into        the at least one cavity    -   a vacuum device designed to generate a negative pressure at        least in the at least one cavity, whereby the generated suction        is directed towards the interior of the rotary conveyor,    -   characterized in that downstream of the fiber feed device at        least one consolidating device is located such that at least a        part of the filled cavity is subjected to a consolidating        treatment such that the base material at least partly will        adhere to neighboring material.

The product obtained by the device according to the invention is aconsolidated three-dimensional shaped part made of base material, likefibers, and which can be used as trim part directly for a vehicle or canbe further processed, for instance by adding additional layers or byfurther forming to material in a second molding step. Further processsteps may include trimming, cutting, punching, laminating, but notnecessarily a further shaping step.

The Rotary Drum

The rotary drum is a cylindrical drum with an axis of rotation parallelto the circumferential surface. The rotary drum is surrounded bydifferent processing zones positioned parallel to the circumferentialsurface of the drum containing the product shaping area(s) (cavity).Preferably the circumferential surface of the drum is in approximatelyhorizontal position and the first processing zone—feeding the basematerial to the cavities—is located approximately at the high end of thedrum to obtain a fiber feeding that is not against gravity. At least asecond processing zone is located in rotation direction downstream andcontains the consolidation of the base material in the cavity.Eventually a third processing zone—cooling the consolidated material—islocated subsequently. Finally a last processing zone to empty the cavityis located after the second or third zone. Preferably this lastprocessing zone is allocated such that the gravity enhances the emptyingof the cavity. The axis of rotation of the rotary conveyor preferablylies in a plane, which is arranged essentially perpendicular to thedirection of gravitational force. The product shaping area (cavity)preferably extends perpendicular or at least essentially perpendicularto radial lines emanating from the axis of rotation of the rotaryconveyor.

The rotary drum contains at least one product shaping area defined as acavity on its circumferential surface. The product can stretch over theentire circumferential surface in rotary direction or only on part ofit. Depending on the size of the products to be produced the size of theproduct shaping area, as well as the number of such areas on one drumcan vary. It is also possible that different product shaping areas arearranged on one drum, to produce different products. It is also possibleto have a product shaping area that is endless giving a continuousproduct, like a mat of fibers or a continuous band.

The depth of the cavity can vary to obtain a preform that is threedimensional in form, having an area weight distribution over the widthand length of the preform.

At least the cavity is lined with an air pervious material, to let theair stream flow through, but to stop the fibers from passing, such thatthe cavity is filled up evenly with the base material. If necessary thecavity lining can have a difference in air resistance to increase ordecrease the flow of the mixture of air and base material locally. Thelining can be made of a single layer or multiple layers, preferably of ametal mesh or fine wire cloth in direct contact with the base materialand at the side away from the material a more stronger material like alarger mesh or rough wire, to obtain a stable form for thethree-dimensional shape wanted. The surface of the rotary drum ispreferably easy replaceable. For instance by a sliding mechanism or byusing easy fastening mechanisms to close the surface with the cavitiesaround the circumferential of the rotary drum. Interchangeable surfacesfor rotary drums are known in the art.

Underneath at least the pervious areas, a vacuum device designed togenerate a negative pressure towards the interior of the rotary conveyoris allocated. The vacuum pressure not only secures the base materialduring the feeding process but may also draw air through the part in thelater processing steps like heating and/or cooling.

The vacuum pressure might be adjustable at the different treatmentzones, in particularly a reduction during the heat setting andafterwards the cooling process as well as a reduction to zero during thedemolding process.

The vacuum device is designed to apply a negative pressure on theair-previous product shaping area in order to suck and hold the basematerial, in the cavity during at least one, several or all processsteps. The vacuum device is preferably designed to apply a negativepressure on the product shaping area in the different processing zones.In a preferred embodiment of the invention device for producing thenegative pressure is designed such that the different processing zonescan be adjusted independent and do not interfere with the otherprocessing zones, optionally even in a processing zone, the vacuum mightbe adjusted in sub zones to optimize even further.

During the continuous production of the three Dimensional molded heatset fibrous products the rotary drum preferably turns at a continuousspeed. The speed might be adjustable depending on the products to beproduced. Once the optimum speed is found, the speed can be maintainedconstant during the continuous production of the parts. If a constantspeed is used, all the different treatments, filling of the cavity, heatsetting of the material and eventually cooling as well as the demoldingmust be adjusted to this one constant speed of the rotary drum.

Feeding Device

In the first processing zone the base material is fed into at least partof the product-shaping cavity using a feeding device whereas the productshaping area is moving continuously, preferably at constant speed, inrotary direction. So it is possible that the product-shaping cavityexpands to a larger area than the base material feeding device covers,in such a case the product-shaping cavity will gradually fill up as thecavity moves under the base material feeding device in rotary direction.The base material feeding device is at least covering the largest widthof the cavity in the perpendicular direction to the circumferentialdirection of the drum.

The base material is preferably fibers like natural fibers, as e.g.cotton fibers and/or synthetic fibers, as e.g. thermoplastic fibers,and/or mineral fibers or a combination thereof. Beside fibers the basematerial can comprise further materials, e.g. in the form of flocks,liquids, powder, etc. For example a combination of scraps of a recycledmaterial, like foam, shoddy etc., together with fibers is possible. Partof the base material can be binding material like binding fibers, powderor flakes, which are activated during the thermal treatment in theadjacent process step and/or in a later stage. Also the binding materialwith different activation mechanisms or processes or points can be usedfor instance with different melting temperatures. The material can thanbe preset during the forming and later for instance be combined withadditional layers and finally molded and laminated at anothertemperature activating a second binding material.

For the transport of the base material to the fiber feeding device stateof the art fiber cleaning, mixing and dosing devices can be used. Toensure a good fiber distribution inside the cavity it is of advantagethat the fiber bundles or clusters are opened up and that the materialis fed substantially as single fibers or particles. The base materialcan be transported to the cavity using one or more transport rollers(feeding rollers) or using an air-laid method or a combination thereof.The fiber feed device is designed accordingly. By using transportrollers the base material, particularly the fibers, are laid down in themold cavity, whereas in the air-laid method the base material,particularly the fibers, are blown into the mold cavity.

The base material feeding zone comprises at least one base materialfeeding device along the circumference and in the direction of rotationof the rotary drum. The use of multiple fiber feeding devices can bepreferential if a layering of material is wanted or to obtain a certainmaterial distribution. Also additional spraying devices for treatment ofthe base material for instance with anti flammability agents can belocated over the width of the drum preferably in rotary directiondownstream of at least the first base material feeding device.

The fiber feed device comprises most preferably a carding unit with acarding roller. The carding roller has the function of refining andmoving the fibers from feeding rolls towards the product shaping area. Afurther function of the carding unit is to scrape the excess of fibers.The base material feeding stage of a fiber-feeding device preferablyextends only along a relatively short peripheral distance in directionof rotation in order to reach a high fiber density in the cavity mold.

As the speed of rotation of the drum is constant and continuous it ispreferred that the volume of base material fed can be regulated. Ways ofregulating material feeding streams are known in the art.

Heating

At least one heating device is allocated to a subsequent secondprocessing zone. In the second processing zone the shaped product isheated in order to consolidate the material. This can be a partialconsolidation to obtain a stabilized preform, that keeps its shapeduring transport, or a full consolidation, to use the three-dimensionalshaped material directly as, or for, the final product, without furtherneed for consolidation and or forming.

As a heating device different technologies can be used like heatradiation, for instance using infrared radiation, or convective heattransfer, for instance using a hot fluid, preferably hot air or steam.Also a combination of technologies can be applied subsequently or inparallel. The choice of heating technology is dependent on the basematerials used and the shape and size of the final product. Contactheating is less preferred for a consolidation of the products emphasizedas the time to heat up the material throughout is too long, this mightdamage the surface. However it might be an option if for instance tolaminate to the visible surface of the base material while still in thecavity an additional covering layer.

All the heating devices are at least covering the largest width of thecavity in the perpendicular direction to the circumferential directionof the drum.

As the drum is continuous and constant moving in rotary direction thedwell time in the heating area is only dependent on the area that iscovered by the heating device in circumferential direction. However theheating process of the product and therefore the amount of consolidationcan be regulated by the temperature differential between the product andthe heat load. Preferably the heat device can be regulated to formdifferent zones with different heating temperatures in the rotarydirection to control the process. For instance by using one heat sourceand but different pressure and/or airflows in different zones.

In the consolidating processing zone the heating device must be able totransfer enough heat into the base material in the cavity that mighthave different thicknesses, e.g. from 50 to 300 mm in order to carry outthe consolidation or fixation, respectively, or the pre-fixation orpre-consolidation, respectively. Therefore, preferably hot blown air orsteam is used to heat up the shaped product. However, if the air speedis too high, a deformation or even the destruction of the instable,shaped product can occur. The airflow is preferably directed in a radialdirection towards the axis of rotation of the rotary conveyor, i.e. fromthe outside to the inside of the drum. The airflow is helped by theexisting vacuum suction located inside the drum and that is already usedfor the filling of the cavity. Preferably the vacuum is set up such thatthe different processing zones do not interfere with each other.

Within the second processing zone containing the heating device one, twoor even more than two heating or temperature zones, respectively withdifferent temperatures can be provided. In these heating zones thetemperature can preferably be set individually and independent from theother heating or temperature zones, respectively.

Due to the heat setting of the base material in the product formingcavity the base material is fixed in position this will prevent thedisadvantageous of the prior art, in particularly the material will upondemolding no longer be able to slide out of position therefore retainingthe desired three-dimensional shape. In addition, the edges obtainedstay sharper and eventually holes are now possible in the technicaldesigns of the new parts, without the necessity to cut them out againlater. In a system without heat setting this was not possible as thefibers would slide upon unloading the mold, softening the part edges andfilling small holes again with fiber material.

Demolding

Downstream of the consolidating process zone the consolidated productcan be demolded in a subsequent processing zone. The three-dimensionalshaped, consolidated product is removed from the product-forming cavity.In the simplest form the product can be transferred to a table, or otherform of stationary device that is used for collecting the consolidatedproducts, or it is in the form of a conveying device for transport ofthe consolidated product for further processing, for instance a conveyerbelt or robotic transport or it is a combination depending on the actualproduct produced.

Cooling

In a further development of the invention the product-shaping devicefurther contains an additional zone before the demolding, to which acooling device is allocated. The cooling zone is arranged along thecircumference and in the direction of rotation of the rotary conveyorbetween the consolidating zone and the demolding zone. In the coolingprocessing zone the previously heated shaped product is cooled as afurther step of the initial solidification. The fiber feed device, theat least one heating device, the eventually cooling device and thetransfer device and hence the corresponding processing zones arestationary arranged alongside the peripheral surface of the rotaryconveyor during the production of the consolidated three-dimensionalproduct. Optionally the cooling device in the cooling zone can bereplaced with an additional heating device for optimal flexibility inthe use of the machinery. The preferred solution for cooling the productwould be the use of a fluid stream preferably in the form of airflow,either at ambient temperature or cooled to optimize the cooling process.The cooling of the part can also be helped by the use of negativepressure in the product-forming cavity.

Other Processes

In addition to the filling of the cavity, the consolidation of thematerial and the demolding eventually an additional process step mightbe integrated in the machine and process according to the invention.Either before or during the heating and/or cooling process step the basematerial might be compacted. For instance by increasing the pressureduring the heating and/or cooling phase, or just before starting theconsolidation but after the fiber feeding. For instance with a pressureroller or by using an air flow or increasing the negative pressure in atleast the part of the cavity that is filled with the base material.

Method of Producing

For carrying out the method of manufacturing a three-dimensional shapedconsolidated product containing base material an apparatus as describedabove is used. The method comprises steps of: providing a device havinga rotary drum with at least one product-shaping area in the form of acavity provided on a peripheral surface thereof, the rotary drumarranged for sequential rotation through a plurality of processingzones; feeding the base material into one of the product-shaping areasas the product shaping area rotates through a feeding zone of thedevice, resulting in a loose fiber base material in the cavity;consolidating the loose fiber base material by at least heating thecavity as the product-shaping area rotates through a consolidation zoneof the device, resulting in at least partial consolidation of the basematerial by heat-setting; cooling the at least partially-consolidatedbase material as the product-shaping area rotates through a cooling zonethat either actively or passively cools the at leastpartially-consolidated base material in the cavity, resulting in aconsolidated three-dimensional shaped product; demolding theconsolidated three-dimensional shaped product as the product-shapingarea rotates through a demolding zone, which is positioned on the devicesuch that gravity at least assists in the demolding of the product; androtating the product-shaping area back into the feeding zone to completethe rotational cycle.

While the invention has been described in present preferred embodimentsof the invention, it is distinctly understood that the invention is notlimited thereto, but may be otherwise variously embodied and practicedwithin the scope of the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic drawing of the device according to theinvention.

FIG. 2 shows a schematic drawing of the device according to theinvention from a different angle.

FIG. 3 shows an example of a consolidated product preform or endproduct.

FIG. 1 shows the device according to the invention. The core of thedevice forms a rotary drum 3 with at least one cavity 4. The surface isat least partially pervious at the areas of the cavity forming the shapeof the wanted product. In the cavity at the side facing the fiber streamthe fibers are collected until the cavity is full. Preferably a devicefor elimination of excess material is given, before the consolidationzone. A take-off roller or a scraping knife, or alternative solutionsknown in the art can be used for this purpose. Another solution is acombination with the feeding device.

Inside the drum a device or means for producing a negative pressure inthe cavity where the product is formed is located. This can be forinstance a vacuum device or connections to an external vacuum device.The connections to the vacuum device can be built independently for thedifferent processing zones. Airstreams through the cavity are shown witharrows.

Due to the rotary movement the cavities will pass different processingsteps or zones. These different processing steps or zones are asfollows:

-   -   A. Feeding of the base material into the cavity;    -   B. Consolidation of the base material collected in the cavity;    -   C. Eventually cooling of the consolidated material in the        cavity;    -   D. Demolding of the three-dimensional shaped consolidated        material from the cavity.

The device 2 in zone A is an example of such base material feedingdevice that can be used according to the invention. The fibrous streamis fed in the cavity using a carding roll which at the same time alsoremoves surplus material as disclosed in WO 2007/134812.

The filled cavities 4 are passing in zone B at least one consolidatingdevice for instance a heating device for thermal treatment of the cavityfilled with base material to heat-set the material. In the example twothermal zones are used, b1 and b2, whereby the temperature Tb1 isdifferent from Tb2. As the transfer of heat is dependent on the materialproperties as well as the temperature of the material, it might benecessary to keep a certain delta between the temperature of the fluidused and the temperature of the product. In particularly care has to betaken that the material is not damaged—overheated and burnt—on thesurface, as this can have a negative effect on the product quality. Theuse of different temperature zones has the advantage that the amount ofheat transferred can be adjusted more optimally. An example of atemperature zoning can be a heat up zone and a zone where thetemperature is kept constant at a higher level. The consolidation of thebase material is dependent on the overall heat that is put into thematerial. Preferably a hot air flow, the temperature of the hot air andeventually the pressure in the treatment zone can be adjusted.

Downstream of the consolidating process zone the consolidated productcan be demolded in a subsequent processing zone D. The three-dimensionalshaped, consolidated product 8 is removed from the product-formingcavity. In the simplest form the product can be transferred to a table,or other form of stationary device that is used for collecting theconsolidated products, or it is in the form of a conveying device fortransport of the consolidated product for further processing, forinstance a conveyer belt 7 or robotic transport or it is a combinationdepending on the actual product produced.

FIG. 2 shows the rotary drum 3 with 2 cavities 4, which rotates aroundan axis of rotation 9 and has a certain width w and a certain radius r.With a dashed line the consolidation zone B is given that extends atleast over the largest width of the cavity, but preferably over thecomplete width of the drum W. The dwell time is dependent on the rotaryspeed of the drum, as also the feeding of the cavity, the cooling andthe lay down is dependent on this factor, therefore the dwell time canonly be regulated with the length L of the circumferential area that isopposite the consolidating device as shown in the dashed line.

For instance the cooling area 6 in the cooling zone C in FIG. 1 might beadjustable to extend the consolidating area.

FIG. 3 shows an example of a three-dimensional shaped consolidatedproduct 8 made of base material for instance fibers produced accordingto the invention, with technical design features, that includes are-entrant portion 12, a hole 10 and an area with a thickness reduction11.

What is claimed is:
 1. A method for producing a three-dimensional consolidated fibrous product, comprising: providing a device having a rotary drum with a product-shaping area in the form of a cavity provided on a peripheral surface thereof; providing a first processing zone comprised of a feeding apparatus adapted to feed loose fiber base material into the cavity; rotating the rotary drum to place the product shaping area adjacent to the loose fiber base material feeding apparatus; feeding loose base material into the product-shaping areas as the product shaping area rotates through the feeding zone, which results is filling the at least a portion of the cavity defined by the product-shaping area with loose fiber base material; providing a second processing zone comprised of a heating device that is adapted to consolidate the loose fiber base material by heat setting; consolidating at least a portion of the loose fiber base material by heating the cavity, whereby the fibers in the loose fibrous base material in the cavity are at least partially adhered as the product-shaping area rotates through the second processing zone providing a third processing zone that is adapted to cool the material in the cavity; cooling the at least partially-consolidated base material to form a consolidated base material in the cavity as the product-shaping area rotates through the third processing zone, to form the three-dimensional consolidated fibrous product; providing a fourth processing zone adapted to remove the three-dimensional consolidated fibrous product from the cavity; demolding the three-dimensional consolidated fibrous product as the product-shaping area rotates through fourth processing zone; and rotating the product-shaping area into the feeding zone to complete the rotational cycle.
 2. The method of claim 1, wherein the loose fiber base material comprises at least one of natural fibers, synthetic fibers, binding materials that are activated during the consolidating.
 3. The method of claim 1, wherein the third processing zone employs active cooling between the second processing zone and the fourth processing zone, the cooling device configured to direct airflow towards the cavity, the airflow having a temperature less than that of ambient air.
 4. The method of claim 1, wherein the second processing zone delivers thermal energy to the loose fibrous base material by at least one of heat radiation and convective heat transfer, and wherein the heating device does not provide contact heating.
 5. The method of claim 1, wherein the second processing zone is comprised of a first heating zone and a second heating zone, and wherein the at least one heating device is configured to provide a heat of a first temperature to the first heating zone and heat of a second temperature to the second heating zone.
 6. The method of claim 1, wherein the cavity spans a width of the rotary drum.
 7. The method of claim 1, wherein the feeding apparatus comprises one or more transport rollers.
 8. The method of claim 1, wherein the feeding apparatus is a carding roller.
 9. The method of claim 1, wherein the rotary drum employs a vacuum device designed to generate a negative pressure at least in the at least one cavity, thereby generating suction directed towards an interior of the rotary conveyor.
 10. The method of claim 9, wherein the negative pressure is comprised of a first negative pressure and a second negative pressure, the first negative pressure and the second negative pressure being different.
 11. The method of claim 1, wherein the cavity is lined with an air pervious material selected from a group consisting of metal mesh and wire cloth.
 12. The method of claim 11, wherein the air pervious material has a first portion that provides a first air resistance and a second portion that provides a second air resistance.
 13. A three-dimensional consolidated fibrous product manufactured by the method of claim
 1. 